What’s Wrong With Human-Animal Chimeras?

WASHINGTON — Scientists are creating human-animal chimeras at several laboratories throughout the U.S., despite a ban against federal funding of the controversial research. An article in MIT Technology Review revealed that the work, directed at growing human organs for transplantation inside livestock, has resulted in human cells being injected into early animal embryos that have been gestated in sheep and pigs.

Based on interviews with members of three research teams in California and Minnesota, and presentations by scientists at a National Institutes of Health “workshop” on the subject in Maryland in November, the MIT article reported that about 20 human-animal chimeras have been transplanted into female livestock in the U.S. during the past year, although none of the research is published, and none of the gestating embryos were delivered.

The prospect of lab-generated animal-human creatures raises a new quagmire of troubling ethical questions, especially as powerful newCRISPR/Cas9 gene-editing technologieshave developed, which push the possibilities for intermingling species to new boundaries.

“We are not near the island of Dr. Moreau, but science moves fast,” NIH ethicist David Resnik said at the meeting in Maryland. “The specter of an intelligent mouse stuck in a laboratory somewhere screaming, ‘I want to get out’ would be very troubling to people.”

Already, other kinds of human-animal chimeras — including “humanized mice,” created by injecting liver and thymus tissue from human aborted babies into mice soon after they are born — are widely used for creating animal models of disease and testing pharmaceuticals, though widespread practical benefits are yet to be seen. Anexposélast summer of Planned Parenthood’s sale of such fetal tissues for profit to researchers has led to public awareness of the practice and vocal opposition to it.

A Step Further

But the research that is under way goes a step further, placing human cells into very early-stage animal embryos, when the tissue can multiply and potentially “differentiate” — or specialize — into any part of the body, including brain or reproductive tissue.